The Internet and the World Wide Web have experienced tremendous growth in the past two decades with millions of new websites being added every year. The downside of this is that it becomes harder and harder for Internet users to find relevant information on the Web. Internet search engines server an important function of helping users to find information on the Web. A typical search engine operates as follows: it use a Web crawler to collected information about websites on the Internet and identify keywords (i.e., words of relative importance) occurring in titles, subtitles, meta tags and other sections of Web pages. The search engine then creates and constantly updates an index of all identified Web pages and the keywords occurring therein. Generally, the Web pages are organized in the index based on popularity or frequency of their access by users. Finally, when a user access the search engine via a Web browser and enters a search query, the search engine searches the index and displays to the user a list of Web pages that contain the words that match the user's query.
Some search engines store users' Web browsing history in a browsing log. Typically, a browsing log includes a list of Web page addresses (e.g., Uniform Resource Locators (URLs)) visited by a user during one or more browsing sessions and related metadata, such as the Web page titles and the date and time the Web page was viewed by the user. For example, the browsing log may be stored locally by the Web browser application in a memory or storage of the user's computer. Alternatively, the browsing log may be stored on the search engine servers. Analysis of browsing logs may provide diverse and valuable information about users' interests and search goals. This information may be used by the search engine to improve accuracy of the search results during subsequent Web searches by the user, improve accuracy of targeted advertisements displayed by the Web browser to the users along with the search results, and other purposes. Therefore, there is a need for an effective mechanism for analyzing browsing logs to determine the intent or goals of Web searches of users.